This CORE grant is intended to provide the baseline level of support required to ensure the maintenance of a research source, the individual project-associated research of which is supported by a number of separate project research grants. All these separate projects share a common modality and are directed to a common goal: the use of radiation in improving understanding and its genesis and treatment. In a sense separate but in reality indistinguishable from the pure research which is the primary function of this program, the CORE group is also engaged in training, both to provide an effective means of continually evaluating and enriching its own research and to ensure the appreciation and perpetuation of different phases of it by others. This proposal, therefore, is aimed at a continuation of a core program which comprises three major components: (1) support of those service-type functions common to the several research and training projects, including animal colony maintenance, tissue culture and bacteriological glassware and media preparation, histopathology laboratory, and administrative/secretarial functions; (2) salary support for key scientific professional personnel; (3) modest support for new pilot research projects prior to application for full- scale support.